Solidifying sulphur



R. F. BACON AND H. S. DAVIS.

SOLIDIFYING SULPHUR.

APPLICATION FILED MAY 31. 1921.

Patented June 20, 1922.

1&193911.

awumato'cs 1 Mgfigw v W sag/ 4a UNITED STATES PATENT OFFICE.

RAYMOND F. BACON AND'HAROLD SIMMONDS DAVIS, OF PITTSBURGH, PENNSYL- VANIA, ASSIGNORS TO TEXAS GULF SULPHUR COMPANY, OF BAY CITY, TEXAS,

A CORPORATION OF TEXAS.

SOLID IFYING SULPHUR.

Specification of Letters Patent.

Patented June 20, 1922.

To all whom it may concern:

Be it known that we, RAYMOND F. BACON, a citizen of the United States, and HAROLD Smnosns Davis, a subject of the King of (treat Britain. both residing at Pittsburgh, county of .-\lleghen v, State of Pennsylvania, have invented certain new and useful Improvements in Solidifying Sulphur; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the solidification of molten sulphur, and has for its ob ject the provision of an improved method of solidifying molten sulphur. More particularly, the invention relates to improvements in the production of sulphur by underground fusion with the discharge of molten sulphur at the surface of the ground and in this connection the invention aims to provide an improved method of solidifying such molten sulphur in a form suitable for handling and transportation from the sulphur fields to the consumers.

In the production or mining of sulphur by underground fusion, for example, in cordance with the well known 'Frasch process, a fusing fluid, such as superheated water, is conveyed to the underground sulphur deposit where its heat is utilized in fusing the sulphur and the fused sulphur is raised to the surface of the ground in a molten condition by suitable agencies, such as an air lift pump.

The satisfactory disposition of the molten sulphur as it is discharged at-the surface of the ground from the so-called sulphur wells presents certain peculiar difficulties. At the present time, it is the customary practice to solidify the sulphur in the form of a huge block or pile containing many thousands of tons of sulphur. Thus, in

accordance with the present prevailing practice, the molten sulphur is conveyed from the sulphur wells to a bin made up of four enclosing walls extending an appropriate distance above the ground level. The enclosing walls are frequently several hundred feet in length and are designed to hold or enclose a huge quantity of sulphur The molten sulphur flows into this bin or enclosure and eventually solidifies into a huge block or pile. In actual practice. many weeks and frequently months elapse before this block of sulphur becomes solid throughout its entire mass.

The block or pile of sulphur, formed as above described, must be broken up for the subsequent handling and shipment from the sulphur field to the consumer. To this end. it Is necessary to blast the sulphur pile in substantially the same manner that rock is blasted. By repeated blasting and considerable manual labor, the sulphur is finally prepared for loading, usually by automatic loading machinery, into freight cars or other conveyances of transportation. The present practice of solidifying the molten sulphur thus involves the formation of a huge pile of solid sulphur and the subse quent breaking up of .this pile of sulphur into suitable form for convenient handling and transportation. The present practice in this respect necessitates the provision above ground of an enormous quantity of sulphur since While one pile or block of sulphur is being broken down and shipped, another block must he in progress of formation, and on this account many thousands of tons of sulphur are constantly maintained above ground. This is obviously an uneconomical procedure and it is extremely desirable that some more satisfactory method of solidifying sulphur be provided by which the molten sulphur may be prepared for shipment within a relatively short time after it is discharged from the sulphur wells. thereby reducing the amount of sulphur which must be accumulated above ground.

The present invention contemplates the provision of an improved method of solidifying large quantities of molten sulphur in a relatively short interval of time. More particularly the invention aims to provide an improved method of solidifying molten sulphur as rapidly as it is discharged from the aforementioned sulphur Wells in a continuous manner and in a form requiring little, if any, subsequent preparation for convenient handling and transportation. Thus, in accordance with the method of the invention, as applied to the-production of sulphur by underground fusion, the molten sulphur from the sulphur wells is solidified into a mass of the desired thickness by successively cooling and solidifying overlaying films of molten sulphur in such a manner that each preceding film of sulphur is substantially solidified before the succeeding film of molten sulphur is overlayed thereon. Another aspect of the invention involves cooling and solidifying a relatively thin layer of molten sulphur and then sue cessively adding to this layer of sulphur and successively cooling and solidifying a plurality of similar thin layers of molten sulphur. If desired, the cooling of the films of molten sulphur may advantageously be hastened by the application of a cooling medium to the exposed surfaces thereof. such, for example, as the application of a draft of cooling air to such surfaces. Throughout this specification and the appended claims, we intend to define by the term film a relatively thin layer of sulphur not exceeding about 0.05 inch in thickness.

In all of the heretofore customary methods of cooling molten sulphur to the solid state, either by granulation or moulding. the sulphur has been cooled in an individual unit which is solidified on the. surface while the inside is still liquid. solidification then proceeds inward, while the heat of fusion is conducted outward through the steadily increasing mass of solidified sul' phur. Since solid sulphur is one of the poorest known conductors of heat, it is evident that the time required to solidify such a unit of sulphur will rapidly increase with its mass, and will not be greatly influenced by the amount of cooling applied to the outer surface.

In accordance withour improved method of solidifying molten sulphur. the molten or liquid sulphur is solidified in very thin layers. each layer being added immediately after the previous one has solidified. By this method. it is possible to build up a block of solid sulphur of any desired thickness while practically all the heat of solidification has been carried off each time through a thin layer of sulphur. It should be pointed out here that, in comparing two blocks of sulphur, one poured in a single layer, the other in a great many layers, the time saved in cooling in the latter case renders negligible the fact that in the former case all of the sulphur has an equal lengthof time for solidification. The total length of time re quired to cool a block of sulphur made in thin layers will be proportional only to the total thickness of the block. It is also to be observed that, since each layer of liquid sulphur fills up any cavities formed by shrinkage of the previous layer on cooling. the resulting block of sulphur is considerably denser than one of the same size poured in a one layer.

\Ve have conducted an extensive series of investigations and researches with the view of determining the rates of cooling of sulphur in thin layers. In these investigations, we have used a pan of galvanized iron one foot square and two inches deep. Thin layers of liquid sulphur of recorded temperatures and weights were poured into this pan and the times required for solidification taken with a stop watch by a second ob- Time required to cool liquid sulphur at various temperatures to the solid state. Each layer contained lb. sulphur, 'was spread over 1 sq. ft, and had an estimated thickness of 0.024 in.

- Calcu- Tlme Temp. of Iated time Conditions. liquid equlred to 00011 trials sulphur. to lb. per 1 layer. Sq. {L

C. .F. Sec. Sec. 36 130 266 35-40 160 7 130 266; 10-15 50 5 120 248! 35-40 140 4 120 248i 12 48 4 115 239, 25-35 120 3 115 239 11 44 since the heat of fusion of sulphur is 11.5 calories per gram and the heat given out in cooling from 130 to 115 C. is only 4.2 calories per gram.

The following table represents the results obtained by us in a further series of investigations'to determine the time required to cool layers of sulphur of various thicknesses to the solid state:

T'ime required to cool sul hm" layers of various thicknesses to t e solid state.

Calcu- Calcu- Wt. of lated lated sulphur thick Condi- Tem Time for solidificatime for per ness of tions. tion. 1 lb. per layer sulphur sq. ft. to layer. solidify.

' No fan... 125 35 sec Withfan. 125 10sec...... 40sec. With fan. 130 22 sec. 44 sec. With fan. 130 85 sec. 85 sec. With fan. 130 5 min. 150 sec. With fan. 130 Over 8 nnn., say 9 180 sec.

min., but undoubtedly it was longer.

From our investigations we have determined that in layers up to 0.025 to 0.050 inch in thickness the rate of cooling and solidification of molten sulphur is practically constant. This is probably due to the fact that the layer of sulphur solidifies as a whole so that no insulating surface is formed. As the thickness of the layer of sulphur is increased beyond about 0.05 inch. the rate of cooling and solidification rapidly decreases. In the case of such thicker layers of sulphur, the surface of the layer solidifies and forms an insulating coating over the interior which remains .liquid much longer than does the surface.

The following table indicates the results of certain investigations conducted to show the relative rates of cooling of somewhat thicker layers of sulphur with and without artificial surface cooling? Thickness of sulphur layers poured en masse 1% in. Total wezght in pan (1 sq.ft.), 1.5 lbs.

No. 2 (with fan playing No. 1 (without fan or water over surface and water at cooling). 5 C. runnlng under bottom of pan).

Time.

0 min. Sulphur at 130 C. poured Sulphur at 130 C. poured into pan.

into pan. Surface solidified. Surface layer in. thick.

2 min. 10 min. 12 min.

'o'r'ys'tiiiiiiat'ib'ri star tell '61'1' su ace.

Surface all solidified Surface layer gin. thick.

solidified layer on bottom w in. ck. Unsolidified center layer in. thick.

17 min.

20 min. solidified layer on bottom %in. thick.

30 min.

Unsolidified pasty massin center.

40 min.

In each of the investigations recorded a above. the sulphurblock was, at the end of one hour, still fragile on account of its unsolidified central portion. This weak central portion will always exist in masses of sulphur cooled in this manner up until the time when solidification is absolutely complete throughout the whole mass. This results from the: fact that liquid sulphur on solidifying contracts as much as 13% so that when a large block of sulphur is cooled the solidified sulphur is. pulled inward until it is strong enough to resist the tension caused bythis contraction, then as solidification proceeds inward crystals of monoclinic sulphur are formed. separated by liquidand-empty spaces. This pasty mass can have little tensile strength until the crystals are cemented together; that is,;until the last traces of sulphur have solidified. As a result, a block of sulphur solidified in a single layer of considerable thicknesswill show a tendency to split at the center during the removal from its containing vessel.

In the accompanyingdrawings, we have diagrammatically illustrated a construction of apparatus designed for the practice of our improved method of cooling and solidifying molten sulphur. In these drawings Fig. 1 is an elevation partly in section of the apparatus;

Fig. 2 is a transverse section on the section line 22 of Fig. 1; and

Fig. 3 is a detailed sectional View on the section line 33 of Fig. 2.

Generally stated. the apparatus illustrated in the accompanying drawings is arranged to build up blocks of sulphur by feeding molten or liquid sulphur in thin layers from nozzles to a belt conveyor and successivel cooling these thin layers of sulphur, pre erably with the assistance of an air draft. The sulphur feeding nozzles should be of a size sufficient to give a uniform coating of 0.025 to 0.050 inch in thickness and should be sufficiently 1 far apart to allow each layer of sulphur to solidify before the next layer is overlaid or superimposed. For a final block f sulphur one inch in thickness. this would require from 20 to 40 sulphur-feeding nozzles spaced at intervals of 2.5 to 5 feet for a belt 100 feet long.

Referring now to the accompanying drawings, there is illustrated a tank '10 adapted to contain a liquid cooling medium 11 such as water, which may be conveniently supplied to the tank through an inlet pipe 12 and withdrawn through an outlet pipe 13. An endless conveyor belt 14 is operatively mounted in the tank 10. and may be driven atuniform speed in any suitable manner. The upper portion of the belt 14 is supported and guided by spool-like rolls 15 while the lower portion is supported by cylindrical rolls 16. The configuration of the ends of the spool rolls 15 is such as to form the upper. portion of the conveyor belt into an elongated receptacle for holding the sulphur. At each end of the tank 10, the

bring the upper portion of the belt 14. at each end. above the level of the cooling liquor 11.

The molten sulphur flowing from the sulphur wells is conveyed in its moltencondition by any appropriate means to a storage basin 1?. The storagebasin 17 may be constructed of any appropriate material suitable for holding molten sulphur. and may be built either above the ground or in the ground. An elevated tank 18 is arranged to be supplied with molten sulphur from the storage basin 1? by means of a pump 19. The level of the molten sulphur in the tank 18 is maintained constant by means of an overflow 20. so that the molten sulphur in the tank 18 is always under a uniform static head. A feedpipe 21 conveys the molten sulphur from the tank 18 to appropriate distributors or sulphur feedingnozzles 22. 3

The distributors 22 consist of a trough like device 23 arranged to uniformly spread the molten sulphur across the entire width of the belt 14. The spreader 23 is steamjacketed and is adapted tobe maintained at an appropriate temperature. to prevent solidification of the sulphur therein by means of a steam feed pipe 24. (Me end of the spreader 23 is provided with an adjusting nut 25 so as to regulate the flow of molten sulphur from the spreader in a uniform layer or sheet.

The spreaders 23 are supplied with molten sulphur by the depending pipes 26 communicating with the feed pipe 21. The amount of sulphur fed to each spreader 23 may be regulated by a needle valve 27. The

feed pipe 21 is also steam jacketed so as to maintain the sulphur flowing therethrough in a fluid or molten state.

A compressed air cooling system comprising a supply pipe 28 and distributors 529 is provided for directing a draft of cooling air against the exposed surface of the sulphur on the conveyor belt 1 1. The air distributors 29 are arranged at appropriate intervals throughout the length of the conveyor belt. It will, of course; be understood that other means may be employed. for applying a draft of cooling air to the exposed surface of the sulphur.

The operation of the apparatus illustrated in the drawings is substantially as follows: Molten sulphur under-a substantially uniform and constant pressure is fed from the tank '18 to the distributors 22. By means of the series of distributors a plurality of relatively thin overlying layers of molten sulphur are added to the conveyor belt in such a manner that each preceding layer of sulphur is substantially solidified before the succeeding layer of molten sulphur is overlaid thereon. The layer of moltensulphur fed to the conveyor belt by each distributor-22 does not exceed in thickness 0.05 inch. \Ve thus have throughout the length of the conveyor belt a mass of sulphur varing in thickness from approximately {L025 inch to the desired thickness of. the sulphur as it is discharged from the conveyor belt, say approximately one inch. At the discharge end of the conveyor belt l-l. themass of solidified sulphur is received by a platform 30 and conveycd by any appropriate instrumentalities to places of storage or shipment. If it is desired to break up the sulphur discharged from the conveyor belt into smaller sizes, appropriate crushing apparatus may be provided for that purpose.

As compared with the present vat or bin system of cooling and solidifying sulphur, the method of the invention possesses the following advantages. Sulphur directfrom the wells is straightwaysolidified in a form suitable for shipment. thus preventing the tie-up of stock necessary in the fat or bin System. The fact that the sulphur from the wells is immediately solidified tends to pre vent discolorimition from any oil which may be present in the mined sulphur. Sulphur containing oil. if held at a temperature of 130 C. for several days. turns very dark in color. It is not at all improbable that this colorizatiou results during the solidification of the sulphur in accordance with the present vat or bin system of cooling. since large quantities of sulphur must in that system remain liquid for a very long time.

The method of cooling and solidifying sulphur in accordance with the present invention possesses distinct advantages over any heretofore proposed method with which we are acquainted of cooling and solidifying sulphur in single layers. In the first place, the method of the invention-enables the production of a much larger out mt of solid sulphur. because of the greatly increased speed of cooling. In the case of solids or blocks of sulphur two inches in thickness. the rate of cooling by the method of the invention is at least three times as rapid as in a singlelayer cooling process. By. the method of the invention, the bottom or initial layer of sulphur is cooled for a longer proportional time and hence has opportunity to loose itself from the container or conveyor belt. The block or slab of sulphur formed by the method of the invention is homogeneous and not softer at the center than at the edges, and as a result. there is less danger of collapse when removed from the container or conveyor belt. The sulphur block or slab formed by the method of the invention is moreover denser and harder than one cooled en masse and is utterly lmpervious to water and the percentage of fines on breaking is also small.

The method of the invention may, with advantage, be employed for solidifying molten sulphur from any source. However, the principles of the invention are more particularly applicable to the production of sulphur by fusion underground with the discharge or delivery of molten sulphur at the surface of the ground. As applied to this method of producing sulphur, the present invention enables a rapid and efficient solidification of the molten sulphur delivered by the sulphur wells.

It will, of course, be understood that the apparatus represented in the accompanying drawings is intended to illustrate one satisfactory arrangement for carrying out the method of the invention. We do not wish or intend to limit the invention to this particular, construction ofapparatus or to an apparatus of this type, since it will be evident to those skilled in the art that the improved method of the invention may be carried out in various forms and types of apparatus.

Weclaim:

1. The method of solidifying molten sul-. phur which comprises building up a mass of solid sulphur by successively cooling and solidifying a plurality of overlying films of molten sulphur.

2. The method of solidifying molten sulphur which-comprises cooling and solidifying a film of molten sulphur, and then successively adding to said film of sulphur and successively cooling and solidifying a plurality of similar films of molten sulphur.

3. The method of solidifying molten sulphur which comprises building up a mass of solid sulphur by successively cooling and solidifying a plurality of overlying films of molten sulphur, the cooling of the films of molten sulphur being hastened by the application of a cooling medium to the exposed surface thereof.

4. The method of solidifying molten sulphur which comprises building up a mass of solid sulphur by successively cooling and solidifying a plurality of overlying films of molten sulphur, the cooling of the films of molten sulphur being hastened bythe application of a draft of cooling air to the exposed surface thereof.

5. The method of solidifying molten sulphur which comprises successively cooling and solidifying a plurality of overlying films of molten sulphur in such a manner that each preceding film of sulphur is substantially solidified before the succeeding film of molten sulphur is overlaid thereon and thereby building up a mass of solid sulphur of a total thickness several times exceeding the individual thickness of the successively cooled and solidified films of ulphur.

6. The improvement in the production of sulphur by underground fusion with the dis charge of molten sulphur at the surface of the ground. which comprises building up a mass of solid sulphur by successively cooling and solidifying a plurality of overlying films of molten sulphur in such a manner that each preceding layerof sulphur is substantially solidified before the succeeding layer of molten sulphur is overlaid thereon.

7. The improvement in the production of sulphur by underground fusion with the discharge of molten sulphur at the surface of the ground, which comprises cooling and so lidifying a film of molten sulphur, and successively adding to said film of sulphur and successively cooling and solidifying a plurality of similar films of molten sulphur in such amanner that each preceding film of sulphur is substantially solidified-before the succeeding film of molten sulphur is added.

8. The improvement in the production of sulphur by underground fusion with the discharge of molten sulphur at the surface of the ground, which comprises building up a mass of solid sulphur by successively cooling and solidifying a plurality of overlying films of molten sulphur.

9. The improvement in the production of sulphur by underground fusion with the discharge of molten sulphur at the surface of the ground, which comprises building up a mass of solid sulphur by successively cooling and solidifying a plurality of overlying films of molten sulphur, the cooling of the films of molten sulphur being hastened by the application of a cooling medium to the exposed surface thereof.

10. The improvement in the production of sulphur by underground fusion with the discharge of molten sulphur at the surface of the ground, which comprises building up a mass of solid sulphur by successively cooling and solidifying a plurality of overlying films of molten sulphur in such a manner that each preceding film of sulphur is substantially solidified before the succeeding film of molten sulphur is overlaid thereon, the cooling of the films of molten sulphur being hastened'by the application of a draft of cooling air to the exposed surface thereof.

11. The method of solidifying molten sulphur which comprises successively cooling and solidifying overlying films of molten sulphur successively deposited upon a moving carrier and thereby forming a mass of solid sulphur of a total thickness several times exceeding the individual thickness of the successively cooled and solidified overlying films of sulphur.

12. The method of-solidifying molten suL phur which comprises building up 21' mass of" solid sulphur by suc-cessively Pooling and soli-difying a plurality of overlying films of molten sulphur successively depositerhupon a moving carrier in such a manner that each preceding film of sulphur is substantially solidified before the succeeding film of molten sulphur is overlaid thereon.

13. The method of solidifying molten sulphur which comprises depositing the molten sulphur in surcess-ive' films upon a. moving carrier, and 1n cooling each of saul films of sulphur prior to depositing the next surreed- RAYMOND F. BACON. HAROLD. SIMMONDS DAVIS. 

